(1) Field of the Invention
This invention relates to a process and an apparatus for producing an organic electroluminescent display, more specifically, to a process and an apparatus for producing a metal electrode thereof.
(2) Description of the Related Art
As shown in FIG. 4, an organic electroluminescent display is constructed in such a manner that a transparent electrode 11 made of indium tin oxide (hereinafter, ITO), a layer of organic electroluminescent material 12 and a metal electrode 13 are laminated in order on a transparent board 10.
The metal electrode 13 is usually formed by electron beam evaporation method.
As shown in FIG. 5, a transparent board 10, on which a transparent electrode 11 and a layer of organic electroluminescent material 12 are formed, is set up in a vacuum chamber that is not shown in the figure, then electron beams 3A generated at an electron beam generator 3 are irradiated onto a metal electrode material 1 that is placed in a crucible 2 to form a metal electrode 13, thereby melting the metal electrode material 1 to generate the metal vapor and then, the generated metal vapor is evaporated onto the layer of organic electroluminescent material 12, thereby the metal electrode 13 is formed.
In such a case that the metal electrode 13 is formed by the above-mentioned electron beam evaporation method, as shown in FIG. 5, when the electron beams 3A are irradiated onto the metal electrode material 1, secondary electrons 4 are emitted from the metal electrode material 1 and collide against the layer of organic electroluminescent material 12.
The secondary electrons 4 collide against the layer of organic electroluminescent material 12, causing damage to the layer of organic electroluminescent material 12 and deteriorating a luminous efficiency thereof.
It is therefore an objective of the present invention to solve the above problem and to provide an apparatus for producing a metal electrode of organic electroluminescent display without deteriorating a luminous efficiency of a layer of organic electroluminescent material and a process for producing such a metal electrode.
In order to attain the above objective, a first aspect of the present invention is to provide an apparatus for producing an organic electroluminescent display, in which a metal electrode is formed by electron beam evaporation method, comprising a device for preventing secondary electrons generated at an evaporation source from reaching a display board.
Preferably, the device in the first aspect of the present invention forms a magnetic field in parallel with the display board between the display board and the evaporation source, whereby the magnetic field is formed in a direction crossing at right angles with electron beams irradiated onto the evaporation source.
The device to form a magnetic field is electrically insulated.
Further, the device in the first aspect of the present invention is a lattice-shaped electrode formed in parallel with the display board between the display board and the evaporation source, and a negative voltage is applied to the lattice-shaped electrode.
A second aspect of the present invention is to provide a process for producing an organic electroluminescent display, in which a metal electrode is formed by electron beam evaporation method, comprising the steps of: forming a magnetic field in parallel with a display board between the display board and an evaporation source; and evaporating a metal electrode material of the evaporation source onto the display board by electron beam evaporation method.
A third aspect of the present invention is to provide a process for producing an organic electroluminescent display, in which a metal electrode is formed by electron beam evaporation method, comprising the steps of: forming an electric field in a direction crossing at right angles with a display board between the display board and an evaporation source; and evaporating a metal electrode material of the evaporation source onto the display board by electron beam evaporation method.